In recent years, semiconductor crystallites (fine particles) are drawing attention and are being actively studied. Semiconductor crystallites have a characteristic feature that the emission wavelength of one material can be controlled by controlling the particle size of the material on the basis of quantum confinement effects, and they are expected to be luminescence center materials.
Of these, CdSe crystallite is easily produced and the particle size of CdSe is also relatively easily controllable, so that it has high utility and studies thereof have been advanced. However, the defect thereof is that it has toxicity derived from Cd.
On the other hand, InP crystallite is free of the toxicity problem that Cd has, so that it draws attention for a new luminescence center.
As a method for synthesizing InP, various methods have been known. For example, there are reports of (1) a method in which a mixture of P((CH2)7CH3)3 with OP(CH2)7CH3)3 is used as a solvent, InCl(COO)2 is used as an In material, P(Si(CH3)3)3 (to be sometimes referred to as “P(TMS) 3” hereinafter) is used as a P material and these materials are reacted at 260 to 300° C. for 3 to 6 days to synthesize InP (for example, see “J. Phys. Chem.”, Vol. 98, page 4966 (1994)) and (2) a method in which In(OR)3 is used as an In material, excess P(TMS)3 is used as a P material and these materials are reacted in a boiling pyridine solution to directly synthesize amorphous InP (specifically, InP[P(TMS)3]x) soluble in toluene (for example, see “Polyhedron” Vol. 13, page 1131 (1994)).
However, the above method (1) takes a long time for the synthesis and is poor in productivity, so that it cannot be said that the method (1) is satisfactory in industrial practice. In the method (2), further, generated InP is amorphous and cannot be used as a light-emitting material for the luminescence center.
InP particles obtained according to any conventional method have defects that they are poor in dispersibility in a solution and are liable to precipitate during a reaction.
On the other hand, as a dry process, there is known a method in which InP is formed by a physical vapor deposition method (PVD method) or a chemical vapor deposition method (CVD method). In these methods, however, not only an expensive apparatus is required but also it is difficult to accurately control the atomic ratio of In and P, so that there is a defect that it is difficult to obtain InP having predetermined performances.